1. Field of the Invention
The present invention relates to a method of measuring a mounting accuracy of an electric-component mounting system which mounts at least one electric component (e.g., an electronic component) on a circuit substrate such as a printed wiring board, and particularly to the art of inspecting a plurality of portions of the mounting system that relate to its mounting accuracy.
2. Discussion of Related Art
Recently, there has been a strong demand to improve a mounting accuracy with which an electric-component (EC) mounting system mounts at least one electric component (EC) on a circuit substrate, so as to meet the need to decrease the distances between the lead wires of each EC and/or the need to increase the density of mounting of ECs. To this end, it has been practiced to detect at least one positional error of one of a plurality of portions of the EC mounting system that relate to its mounting accuracy, relative to the other portion or at least one of the other portions. Those portions include an EC holder which holds an EC, a first image taking device which takes an image of the EC held by the EC holder, and a second image taking device which takes an image of a reference mark of a circuit substrate on which the EC is to be mounted. Based on the detected positional error, the EC mounting system controls its EC mounting operation. In the conventional accuracy measuring method, a special measuring device is employed to measure the positional error on the EC mounting system, and the thus measured positional error is used to adjust the mounting system, when the system is manufactured or when the system is subjected to maintenance by user.
That is, the conventional accuracy measuring method needs the special measuring device to measure the positional error from the EC mounting system, and accordingly the user cannot easily measure the error.
Meanwhile, the positional error with the EC mounting system may change because of the deformation of the mounting system as a whole that is caused by the change of temperature of ambient air or by the increase of temperature resulting from the heat generation of one or more servomotors and/or the friction of one or more ball screws. The change of positional error may also be caused by the wearing and/or deformation of one or more parts of the mounting system. Thus, the improvement of mounting accuracy of the EC mounting system needs to measure frequently the positional error from the mounting system and adapt the system to the changes of the positional error. However, in the conventional accuracy measuring method and apparatus, a plurality of positional errors are measured in a plurality of measuring actions (ideally, several tens of measuring actions) in each one positional-error measuring operation, and an average of those errors is obtained to minimize the error of measurement. This means that it is difficult to perform frequently the positional-error measuring operations and adapt the mounting system to the changes of the positional error.
Moreover, in the conventional accuracy measuring method, a characteristic value of the EC mounting system that is obtained as a value relating to its mounting accuracy is treated as if it were constant. More specifically described, a plurality of characteristic values of the EC mounting system are measured in a plurality of measuring actions, and an average of those characteristic values is obtained as a proper characteristic value of the mounting system. However, the proper characteristic value of the mounting system that is obtained once is used as if it were constant till the next positional-error measuring operation is carried out to update the proper characteristic value. In fact, the proper characteristic value changes as the EC mmounting operation of the EC mounting system progresses or as the amount of operation of the mounting system increases.
The present invention provides an accuracy measuring method, an accuracy-measuring-program recording medium, and an electric-component mounting system which have one or more of the following technical features that are described below in respective paragraphs given parenthesized sequential numbers (1) to (25). Any technical feature that includes another technical feature shall do so by referring, at the beginning, to the parenthesized sequential number given to the latter feature. However, the following technical features and the appropriate combinations thereof are just examples to which the present invention is by no means limited. In addition, in the case where one technical feature recites a plurality of items, it is not essentially required that all of those items be simultaneously employed. That is, it is possible to select and employ only a portion (one, two, . . . , but not all) of those items.
(1) According to a first feature of the present invention, there is provided a method of measuring an accuracy with which an electric-component mounting system mounts at least one electric component on a circuit substrate, the electric-component mounting system including at least one component holder for holding the at least one electric component, a substrate supporting device for supporting the circuit substrate, a first image-taking device for taking an image of at least a portion of the electric component held by the component holder, and a second image-taking device for taking an image of at least a portion of the circuit substrate supported by the substrate supporting device, at least two elements out of the component holder, the first image-taking device and the second image-taking device relating to the accuracy, the method comprising the step of measuring, with the electric-component mounting system, at least one positional error of one of the component holder, the first image-taking device and the second image-taking device relative to at least one of the others of the component holder and the first and second image-taking devices.
In the present accuracy measuring method, the mounting accuracy of the EC mounting system is measured with the mounting system itself. Thus, the mounting accuracy can be easily measured and accordingly can be measured frequently. That is, the deformation of the mounting system as a whole that is caused by the change of temperature of ambient air, the heat generation of one or more servomotors, the increase of temperature resulting from the friction of one or more ball screws, etc. can be detected frequently, which leads to improving the mounting accuracy of the mounting system. The first and second image-taking devices may be provided by a single image-taking device. The above-indicated at least one positional error may comprise at least one of (a) at least one positional error of an axis line of one of the component holder and the first and second image-taking devices relative to an axis line of at least one of the others of the component holder and the first and second image-taking devices (e.g., as seen in at least one of an X-axis direction and a Y-axis direction) and (b) a phase or angular error (i.e., a rotation-position error) of an axis line of one of the component holder and the first and second image-taking devices relative to an axis line of at least one of the others of the component holder and the first and second image-taking devices.
(2) According to a second feature of the present invention, there is provided a method of measuring an accuracy with which an electric-component mounting system mounts at least one electric component on a circuit substrate, the electric-component mounting system including at least one component holder for holding the at least one electric component, a substrate supporting device for supporting the circuit substrate, a first image-taking device for taking an image of at least a portion of the electric component held by the component holder, and a second image-taking device for taking an image of at least a portion of the circuit substrate supported by the substrate supporting device, at least two elements out of the component holder, the first image-taking device and the second image-taking device relating to the accuracy, the method comprising the steps of operating the component holder to hold a standard chip, operating the first image-taking device to take at least one first image of at least a portion of the standard chip held by the component holder, operating the component holder to place the standard chip at a prescribed chip-place position, operating the second image-taking device to take at least one second image of at least a portion of the standard chip placed at the chip-place position, and determining, based on the first image taken by the first image-taking device and the second image taken by the second image-taking device, at least one positional error of one of the component holder, the first image-taking device and the second image-taking device relative to at least one of the others of the component holder and the first and second image-taking devices.
In the present accuracy measuring method, both the image of the standard chip held by the component holder and the image of the same chip placed at the chip-place position are taken and, through the medium of the standard chip, the positional error of one of the component holder and the first and second image-taking devices relative to at least one of the others of the component holder and the first and second image-taking devices is measured. Thus, the positional error of one of a plurality of portions of the EC mounting system that relate to its mounting accuracy, relative to at least one of the others of those portions is measured by utilizing the proper functions of the mounting system itself. Thus, the present method does not need such a special jig which is employed in the previously-described conventional method. The standard chip may be one which is manufactured exclusively for measurement purposes only, or one of the proper electric components to be mounted on the circuit substrates. As will be described in DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS, in the case where the change of the relative position between the component holder and the second image-taking device is negligibly small and accordingly the relative position can be regarded as being constant, or in the case where the relative position between the component holder and the second image-taking device is measured in advance and is known already, the present method does not essentially need to determine the position of the component holder. In addition, some error of the actual position of the component holder from its reference or nominal position may not influence the mounting accuracy of the EC mounting system, so long as the component holder can reliably hold the EC. In the last case, too, the present method does not essentially need to determine the actual position of the component holder. The EC mounting system may be one which includes a component holder for holding an EC, and a moving device for moving the holder in directions parallel to an upper surface of a circuit substrate, so that the holder mounts the EC on the substrate; or one which has a fixed EC-mount position where a component holder mounts an EC on a circuit substrate and which includes a substrate supporting device for supporting the substrate and a moving device for moving the substrate supporting device supporting the substrate, in directions parallel to an upper surface of the substrate, so that the holder mounts the EC on the substrate at the fixed EC-mount position.
(3) According to a third feature of the present invention that includes the second feature (2), the step of determining the at least one positional error comprises determining, based on the first image taken by the first image-taking device, at least one positional error of the standard chip held by the component holder, relative to at least one of the component holder and the first image-taking device, and determining, based on the second image taken by the second image-taking device, at least one positional error of the second image-taking device relative to the standard chip placed at the chip-place position.
The determining steps according to this feature are a representative manner of the determining step according to the second feature (2).
(4) According to a fourth feature of the present invention that includes the second or third feature (2) or (3), the step of determining the at least one positional error comprises determining at least one positional error of the second image-taking device relative to at least one of the component holder and the first image-taking device.
The second image-taking device takes the image of the circuit substrate, and the EC mounting system determines, based on the taken image, a position where the EC held by the component holder is to be mounted on the circuit substrate. Accordingly, it is preferable to measure a positional error of the second image-taking device relating to the position on the circuit substrate, relative to the component holder or the first image-taking device relating to the position of the EC. In particular, in the case where the positional error between the first and second image-taking devices is measured, the mounting accuracy of the EC mounting system can be easily improved.
(5) According to a fifth feature of the present invention that includes any one of the second to fourth features (2) to (4), the step of determining the at least one positional error comprises determining at least one positional error of the standard chip relative to the component holder, and modifying, based on the determined positional error of the standard chip relative to the component holder, prescribed control data used to operate the component holder to place the standard chip at the prescribed chip-place position, so that the component holder is operated, according to the modified control data, to place the standard chip at the chip-place position.
In the present accuracy measuring method, the positional error of the standard chip relative to the component holder is determined, and the thus determined error is used to modify the prescribed control data according to which the component holder is operated to place the standard chip at the prescribed chip-place position, as is done in the case where the component holder is operated to mount the EC on the circuit substrate. According to the thus modified control data, the component holder is operated to place the standard chip at the chip-place position. Therefore, the present method can measure an overall mounting accuracy of all the portions of the EC mounting system that relate to its EC-mounting function. However, it is possible to place the standard chip without modifying the control data based on the positional error of the chip relative to the holder. In the latter case, the present method can measure a mounting accuracy of only the portions of the EC mounting system that relate to its EC-mounting function but do not include one or more portions relating to the function of modifying the control data based on the positional error of the chip relative to the holder. The above-described two sorts of mounting accuracies may be measured and a difference of the two accuracies may be obtained. This difference means an accuracy of the one or more portions of the mounting system that relate to the function of modifying the control data based on the positional error of the chip relative to the holder.
(6) According to a sixth feature of the present invention that includes any one of the second to fifth features (2) to (5), the step of measuring the at least one positional error further comprises placing, before the component holder is operated to hold the standard chip, the standard chip at the prescribed chip-place position, so that the component holder is operated to hold the standard chip placed at the chip-place position.
The standard chip may be supplied by a special supplying device each time a mounting-accuracy measuring operation is carried out. In this case, however, the present method need an additional step of removing the standard chip after use. This leads to complicating the measuring operation of the EC mounting system. In contrast, in the present accuracy measuring method, the standard chip is placed, in advance, at the prescribed chip-plate position. Therefore, the mounting system has only to repeat taking up the standard chip from the chip-place position and returning it to the same place, and does not need the special step of removing the used chip, which leads to simplifying the mounting-accuracy measuring operation of the mounting system. In addition, the present method needs only a small amount of standard chips and does not need a special standard-chip supplying device.
(7) According to a seventh feature of the present invention that includes any one of the second to sixth features (2) to (6), the step of operating the first image-taking device to take the at least one first image comprises rotating the component holder holding the standard chip, about an axis line of the holder, to each of a plurality of rotation positions of the holder, and operating the first image-taking device to take a first image of the standard chip held by the component holder at each of the rotation positions thereof, and wherein the step of determining the at least one positional error comprises determining, based on the respective first images taken by the first image-taking device at the rotation positions of the holder, at least one positional error of the standard chip relative to the component holder.
When the EC is mounted on the circuit substrate, it is assumed that the position of the component holder present in the first image taken by the first image-taking device is constant or unchangeable, and a positional error of the position of a predetermined portion (e.g., the center) of the EC relative to the constant position of the holder, determined by the processing of the first image, is obtained as a positional error of the EC relative to the holder. When the mounting accuracy of the EC mounting system is measured, it is also possible to determine a positional error of the standard chip relative to the component holder in the same manner as described above for the case where the EC is mounted on the substrate. In the latter case, however, if the actual position of the holder in the first image is deviated from its reference or nominal position, that deviation cannot be detected. In contrast, in the present accuracy measuring method, the component holder is rotated to rotate the standard chip to each of a plurality of rotation positions where respective images of the standard chip are taken and based on the thus taken images, the center of rotation of the standard chip is determined. This center can be determined as the actual position of the holder, and at least one positional error of the standard chip relative to the position of the holder can be accurately measured.
(8) According to an eighth feature of the present invention that includes the seventh feature (7), the step of determining the at least one positional error of the standard chip relative to the component holder comprises determining, as a position of the component holder, a position of a center of a circle which passes through respective positions of respective centers of the standard chips present in the respective first images taken by the first image-taking device at the rotation positions of the holder.
(9) According to a ninth feature of the present invention that includes the seventh or eighth feature (7) or (8), the plurality of rotation positions of the component holder are equiangularly spaced from each other about the axis line of the holder, and the step of determining the at least one positional error of the standard chip relative to the component holder comprises determining, as a position of the component holder, an average of respective positions of respective centers of the standard chips present in the respective first images taken by the first image-taking device at the rotation positions of the holder.
In the present accuracy measuring method, the position of the component holder can be determined by calculating the average of the respective center positions of the standard chips present in the first images taken. Thus, the positional error between the holder and the chip can be easily determined. As the incremental angle by which the holder is intermittently rotated decreases, the total number of the respective center positions of the standard chips increases, which leads to improving the accuracy of determination of the center position of the holder. However, the total number of image-taking actions and the total amount of processing of the taken images increase and accordingly the overall time needed for each mounting-accuracy measuring operation increases. Therefore, it is preferred that the incremental angle be 90 degrees
(10) According to a tenth feature of the present invention, there is provided a method of measuring an accuracy with which an electric-component mounting system mounts at least one electric component on each of a plurality of circuit substrates, the electric-component mounting system including at least one component holder for holding the at least one electric component, a substrate supporting device for supporting the each of the circuit substrates such that the each circuit substrate is not movable relative thereto, and a moving device for moving the component holder holding the electric component, in a direction parallel to a surface of the each circuit substrate supported by the substrate supporting device, so that the electric component is mounted on the each circuit substrate, the method comprising the step of measuring, while the electric-component mounting system is performing an electric-component mounting operation, the accuracy with which the mounting system mounts the at least one electric component on the each of the circuit substrates, by using at least one portion of the mounting system that can be used without lowering an operation efficiency with which the mounting system performs the electric-component mounting operation.
The present accuracy measuring method can measure, while the EC mounting system is performing the EC mounting operation, the mounting accuracy of the mounting system, without lowering the operation efficiency thereof.
(11) According to an eleventh feature of the present invention that includes the tenth feature (10), the step of measuring the accuracy comprises operating, after the electric-component mounting system has finished, in the electric-component mounting operation, a mounting operation on a first circuit substrate supported by the substrate supporting device and while the mounting system is continuing the electric-component mounting operation including carrying out the first circuit substrate from the substrate supporting device and carrying in a second circuit substrate to the supporting device, the component holder to hold a standard chip and place the standard chip at a prescribed chip-place position, and determining at least one positional error of the standard chip placed at the chip-place position.
While a first circuit substrate is carried out and a second circuit substrate is carried in, the component holder or the first or second image-taking device is not used. This is utilized by the present accuracy measuring method to measure the mounting accuracy of the EC mounting system. Therefore, even while the mounting system is performing the EC mounting operation, the mounting accuracy of the system can be measured without lowering the operation efficiency thereof. In the EC mounting system of the type in which the component holder is moved in directions parallel to surfaces of the circuit substrate to mount the EC on the substrate, if the chip-place position is prescribed at a position which is not on the substrate and where the standard chip does not interfere with the movable parts of a substrate conveying device or the substrate being conveyed thereby, the component holder can be operated to place the chip at the chip-place position, either when the substrate is carried in or out or when the substrate is kept still.
(12) According to a twelfth feature of the present invention that includes the tenth or eleventh feature (10) or (11), the chip-place position is prescribed at a position on the substrate supporting device such that the standard chip placed at the prescribed chip-place position does not interfere with the circuit substrate supported by the substrate supporting device.
In the present accuracy measuring method, the chip-place position is prescribed at a position which is on the substrate supporting device and where the standard chip does not interfere with the circuit substrate. Therefore, both the mounting-accuracy measuring operation and the EC mounting operation can be carried out without interfering with each other. For example, in the state in which the standard chip is placed at the chip-place position, the EC mounting operation can be carried out.
(13) According to a thirteenth feature of the present invention that includes any one of the tenth to twelfth features (10) to (12), the chip-place position is prescribed at a position on a portion of the substrate supporting device that is immovable at least while the electric-component mounting system is performing the electric-component mounting operation.
If the chip-place position is prescribed or predetermined at a position on a movable member of the substrate supporting device, the standard chip which is placed at the chip-place position might be moved when the movable member is accelerated or decelerated. In contrast, since the chip-place position is prescribed on the immovable portion of the supporting device, the present accuracy measuring method is free of that problem. The chip-place position is prescribed within the range which can be covered by the field of view of the second image-taking device.
(14) According to a fourteenth feature of the present invention, there is provided a method of measuring an accuracy with which an electric-component mounting system mounts at least one electric component on each of a plurality of circuit substrates, the electric-component mounting system including at least one component holder for holding the at least one electric component and mounting the electric component on the each of the circuit substrates, the method comprising the steps of measuring, at each one of a plurality of different times, at least one temporary characteristic value relating to the accuracy with which the electric-component mounting system mounts the at least one electric component on the each circuit substrate; and determining, at the each one of the different times, at least one proper characteristic value based on the at least one temporary characteristic value measured at the each one time and at least one temporary characteristic value measured at at least one of the different times that is prior to the each one time.
The characteristic value of the EC mounting system may be a positional error of a portion of the mounting system relative to another portion of the same. In the present accuracy measuring method, since a plurality of temporary characteristic values are measured, the influence of error of measurement to the proper characteristic value can be gradually reduced, and accordingly the proper characteristic value gradually approaches a true characteristic value of the system. In addition, since the plurality of temporary characteristic values are obtained at substantially different times and are utilized on an accumulative basis, the present method can reliably follow the change of the true characteristic value that may occur as the EC mounting operation progresses or as the total amount of operation of the mounting system increases. The present method may be carried out by the EC mounting system itself, or a special, accuracy measuring apparatus which does not belong to the mounting system and measures a mounting accuracy of the mounting system. A new proper characteristic value at the current time may be determined by correcting the proper characteristic value determined at the last time, with a temporary characteristic value measured at the current time, such that the new proper characteristic value is a value between the last proper characteristic value and the current temporary characteristic value. The new proper characteristic value may be any value between the last proper characteristic value and the current temporary characteristic value. In the case where the new proper characteristic value is determined as an internal-division point between the last proper characteristic value and the current temporary characteristic value, the internal-division point may be determined using a predetermined internal-division ratio. Alternatively, the internal-division point may be changed using the total number of times by which the proper characteristic value has been corrected, as recited in the sixteenth feature (16). The internal-division ratio should be determined depending upon how to weigh one of the last proper characteristic value and the current temporary characteristic value relative to the other characteristic value. For example in the case where it is speculated that the change of the true characteristic value will be small, the last proper characteristic value should be weighed more than the current temporary characteristic value.
(15) According to a fifteenth feature of the present invention that includes the fourteenth feature (14), the step of measuring the at least one temporary characteristic value comprises measuring the at least one temporary characteristic value, at the each one time after the electronic-component mounting system has finished a mounting operation on a first circuit substrate and before the mounting system starts a mounting operation on a second circuit substrate following the first circuit substrate.
Between two successive times at which two successive proper characteristic values are determined, respectively, one or more mounting operations on one or more circuit substrates are carried out using the prior one of the two proper characteristic values, i.e., the last proper characteristic value. The total number of temporary characteristic value or values measured at each time may be one or plural. However, such a total number is preferable which can be obtained without lowering the operation efficiency of the EC mounting system. The present accuracy measuring method can reliably follow the change of the true characteristic value which may occur as the EC mounting operation of the EC mounting system progresses or as the total amount of use of the mounting system increases.
(16) According to a sixteenth feature of the present invention that includes the fourteenth or fifteenth feature (14) or (15), the step of determining the at least one proper characteristic value comprises determining, at the each one of the times, the at least one proper characteristic value based on the at least one temporary characteristic value measured at the each one time, at least one proper characteristic value determined at one of the different times that precedes the each one time, and a total number of the different times up to the each one time.
In the present accuracy measuring method, for example, the new proper characteristic value is determined while the above-described internal-division ratio is changed depending upon the total number of the different times up to the current time. The manner in which the internal-division ratio is changed depending upon the total number may be such, that while the total number is small, the new proper characteristic value is a value between the last proper characteristic value and the current temporary characteristic value and nearer to the latter value and, as the total number increases, the new proper characteristic value gradually approaches the last proper characteristic value, or vice versa.
(17) According to a seventeenth feature of the present invention that includes any one of the first to ninth features (1) to (9), the step of measuring the at least one positional error comprises measuring, while the electric-component mounting system is performing an electric-component mounting operation, the at least one positional error of the one of the component holder and the first and second image-taking devices relative to the at least one of the others of the component holder and the first and second image-taking devices, by using a plurality of portions of the mounting system that can be used without lowering an operation efficiency with which the mounting system performs the electric-component mounting operation, the plurality of portions of the mounting system comprising the component holder and the first and second image-taking devices.
The present accuracy measuring method may employ any one of the above-described eleventh to thirteenth features (11) to (13).
(18) According to an eighteenth feature of the present invention that includes any one of the fourteenth to sixteenth features (14) to (16), the step of measuring the at least one temporary characteristic value comprises measuring, while the electric-component mounting system is performing an electric-component mounting operation, the at least one temporary characteristic value, by using at least one portion of the mounting system that can be used without lowering an operation efficiency with which the mounting system performs the electric-component mounting operation, the at least one portion of the mounting system comprising the component holder.
The present accuracy measuring method may employ any one of the above-described eleventh to thirteenth features (11) to (13).
(19) According to a nineteenth feature of the present invention that includes any one of the first to ninth features (1) to (9), the step of measuring the at least one positional error comprises measuring, at each one of a plurality of different times, at least one temporary characteristic value relating to the accuracy, and determining, at the each one of the different times, at least one proper characteristic value based on the at least one temporary characteristic value measured at the each one time and at least one temporary characteristic value measured at at least one of the different times that is prior to the each one time.
The present accuracy measuring method may employ any one of the eleventh to thirteenth features (10) to (13) and the fifteenth and sixteenth features (15), (16).
(20) According to a twentieth feature of the present invention that includes any one of the first to ninth features (1) to (9), the step of measuring the at least one positional error comprises measuring, at each one of a plurality of different times while the electric-component mounting system is performing an electric-component mounting operation, at least one temporary characteristic value comprising the at least one positional error of the one of the component holder and the first and second image-taking devices relative to the at least one of the others of the component holder and the first and second image-taking devices, by using a plurality of portions of the mounting system that can be used without lowering an operation efficiency with which the electric-component mounting system performs the electric-component mounting system, and determining, at the each one of the different times, at least one proper characteristic value based on the at least one temporary characteristic value measured at the each one time and at least one temporary characteristic value measured at at least one of the different times that is prior to the each one time, the plurality of portions of the mounting system comprising the component holder and the first and second image-taking devices.
The present accuracy measuring method may employ any one of the eleventh to thirteenth features (11) to (13) and the fifteenth and sixteenth features (15), (16).
(21) According to a twenty-first feature of the present invention that includes any one of the second to twentieth features (2) to (20), the step of measuring the at least one positional error further comprises prescribing a plurality of chip-place positions which are distant from each other in a direction which is parallel to a surface of the circuit substrate supported by the substrate supporting device and in which a moving device moves at least one of the component holder and the circuit substrate relative to the other of the component holder and the circuit substrate.
The present method can measure, for each of the plurality of chip-place positions, the accuracy with which the moving device positions the component holder and the circuit substrate relative to each other. It is preferred that the plurality of chip-place positions be uniformly distributed over the entirety of the range in which the moving device can cause the relative movement of the holder and the substrate.
(22) According to a twenty-second feature of the present invention, there is provided a method of measuring an accuracy with which an electric-component mounting system mounts at least one electric component on a circuit substrate, the electric-component mounting system including at least one component holder for holding the at least one electric component, a substrate supporting device for supporting the circuit substrate, a first image-taking device for taking an image of at least a portion of the electric component held by the component holder, and a second image-taking device for taking an image of at least a portion of the circuit substrate supported by the substrate supporting device, the method comprising the steps of operating the component holder to hold a standard chip, operating the first image-taking device to take at least one first image of at least a portion of the standard chip held by the component holder, operating the component holder to place the standard chip at a prescribed chip-place position, operating the second image-taking device to take at least one second image of at least a portion of the standard chip placed at the chip-place position, determining, based on image data representing the first image taken by the first image-taking device and image data representing the second image taken by the second image-taking device, a relative angular error between respective angular phases of the first and second image-taking devices about respective optical axes thereof.
The relative angular error between the respective angular phases of the first and second image-taking devices can be determined without requiring essentially that the relative position of the component holder and the first image-taking device be unchangeable, or that the relative positional error between the holder and the first image-taking device be measured. The present measuring method may employ any one of the above-described second to twenty-first features (2) to (21).
(23) According to a twenty-third feature of the present invention, there is provided a recording medium in which an accuracy measuring program is recorded such that the accuracy measuring program is readable by a computer to control an electric-component mounting system to measure an accuracy with which the mounting system mounts at least one electric component on a circuit substrate, the mounting system including at least one component holder for holding the electric component and mounting the electric component on the circuit substrate, the accuracy measuring program comprising the steps of controlling the component holder to hold a standard chip, controlling a first image-taking device to take at least one first image of at least a portion of the standard chip held by the component holder, moving the component holder to a prescribed chip-place position and place the standard chip at the chip-place position, controlling a second image-taking device to take at least one second image of at least a portion of the standard chip placed at the chip-place position, determining, based on image data representing the first image taken by the first image-taking device, at least one first relative positional error between the standard chip and at least one of the component holder and the first image-taking device, and determining, based on image data representing the second image taken by the second image-taking device, at least one second relative positional error between the standard chip and the second image-taking device.
The present measuring method may employ any one of the above-described second to twenty-second features (2) to (22). When the accuracy-measuring program recorded on the present recording medium is used with a computer of a conventional EC mounting system, the mounting system can automatically measure a mounting accuracy or error of its own.
(24) According to a twenty-fourth feature of the present invention that includes the twenty-third feature (23), the accuracy measuring program further comprises modifying, based on the determined first and second relative positional errors, an electric-component mounting program which is used to control the electric-component mounting system to mount the electric component on the circuit substrate.
In this case, the mounting error of the EC mounting system can be automatically removed or reduced.
(25) According to a twenty-fifth feature of the present invention, there is provided an electric-component mounting system, comprising at least one component holder which is for holding at least one electric component and mounting the electric component on a circuit substrate; a moving device which is for moving at least one of the component holder and the circuit substrate relative to the other of the component holder and the circuit substrate, in a direction parallel to a surface of the circuit substrate; a first image-taking device which is for taking an image of at least a portion of the electric component held by the component holder; a second image-taking device which is for taking an image of at least a portion of the circuit substrate; and a control device which controls the component holder, the moving device, and the first and second image-taking devices so that the electric component is mounted on the circuit substrate, the control device comprising a measurement control portion which controls the component holder to hold a standard chip, controls the first image-taking device to take at least one first image of at least a portion of the standard chip held by the component holder, controls the component holder to place the standard chip at a prescribed chip-place position, controls the second image-taking device to take at least one second image of at least a portion of the standard chip placed at the chip-place position, determines, based on image data representing the first image taken by the first image-taking device, at least one first relative positional error between the standard chip and at least one of the component holder and the first image-taking device, and determines, based on image data representing the second image taken by the second image-taking device, at least one second relative positional error between the standard chip and the second image-taking device.
The present EC mounting system may employ any one of the above-described second to twenty-fourth features (2) to (24).